It is well known that if a beam formed by any set of parallel rays of light, of any spectral colour wave, are directed onto a spherical convex surface of any transparent material, the light reflected therethrough will not provide an exact or punctual perfect focus, because of the spherical aberration phenomenon.
In a similar manner, but inversely, from inside any transparent material of convex spherical shape, any possible parallel beam of light will not be focused in punctual perfect focus because of the same spherical aberration phenomenon.
The same results are obtained if, instead of convex spherical surfaces, concave spherical surfaces are used as, in this case, the same aberration will be produced for the elongation of rays, i.e. the virtual focus will not be a punctual focus.
When spherical refraction surfaces are used, it is known that the normal to all refraction points of the spherical curvature is the radius directed to the centre of the sphere. In spite of this, this will not give us a punctual focus, since it is necessary that the curvature should not be so uniformly continuously curved but, on the contrary, that the same has a constant change, from the horizontal axis to the end of the curve.
Also, for the contrary refraction phenomenon, be it from inside the transparent material to the air, the spherical curvature makes the refraction through the extreme sides of the same impossible, or be it from convex surfaces ends, the light will not be refracted because the rays would go out from the curved surface, with an angle greater than the limit refraction angle of the transparent material, thus being reflected instead of refracted. Also for the rays going out from the surface, within the limit refraction angle, the refraction will not be the same for all the parallel rays, and the rays with angles nearer to the axis will be refracted less than the more separate rays and for this reason the refracted rays will cross the axis at different points, the farther away the rays the neater to the central axis of the spherical convex surface they are arranged.
The above cited difficulties will be resolved by employing the lenses without spherical aberration for the two kinds of light refraction and for convex or concave surfaces.
As to a stereoscopic camera, it is commonly known stereoscopic photography without using any lenses, that is made by a vertical lenticular photographic film, from different objectives placed side by side in order to obtain distinct intercalated images to produce a wide viewing zone of stereoscopic photography.
In spite of this, by employing multiple objectives it is not possible to obtain a perfect change in the stereoscopic vision when the viewer laterally translates his head, producing changes in the vision of the distinct adjacent sides of the distinct images of the multiple objectives. For this reason, it is not known a stereoscopic photography with the high quality standards needed by modern audiovisual techniques.